Aqueous liquid formulations of pyrazoline brighteners

ABSTRACT

The claimed liquid formulations contain an organic acid and a branched mono- or di-alcohol. The addition of the alcohol improves the storage stability of the liquid formulations.

It is known to use certain pyrazoline brighteners, which bear basicgroups and are present in the form of their salts with lactic acid, forbrightening acrylic fibers (DE 3 134 942). A commercially availableaqueous liquid formulation of such a brightener contains lactic acid,formic acid and methoxypropanol as well as the brightener. However, thisformulation is still in need of improvement with regard to its stabilityin storage. It is thus an object of the present invention to provideaqueous liquid formulations of pyrazoline brighteners that have improvedstability in storage. It has now been found that this object is achievedwhen a branched mono- and di-alcohol is added to the formulation of thisbrightener type.

The invention accordingly provides aqueous liquid formulations ofpyrazoline brighteners of the formula

where

-   X is O, SO₂, SO₂NZ or a direct bond,-   Y is an alkylene chain which may be interrupted by O, S or CONH,-   Z is H or alkyl,-   R₁ and R₂ are singly an alkyl, cycloalkyl or aralkyl radical or    together the remaining members of an N-heterocycle,-   Z₁ is H or alkyl,-   Z₂ is H, alkyl or aryl, and-   A is an anion of an organic acid,    wherein these liquid formulations contain an organic acid and a    branched mono- or di-alcohol as well as a pyrazoline brightener of    the above formula.

Suitable alkyl radicals R₁ and R₃ are especially those having 1 to 4carbon atoms, which may be substituted by halogen such as fluorine,chlorine and bromine hydroxyl groups, cyano groups, C₁-C₄-alkoxy groups,phenoxy groups, C₂-C₅-alkylcarbonyloxy groups or C₂-C₅-alkoxycarbonyloxygroups.

Suitable cycloalkyl radicals R₁ and R₂ are cyclopentyl and cyclohexylradicals.

Suitable aralkyl radicals R₁ and R₂ are especially benzyl andphenylethyl radicals.

Suitable heterocyclic radicals which can be formed by R₁ and R₂combining with the nitrogen atom are for example pyrrolidine,piperidine, imidazole, morpholine and thiomorpholine radicals.

Suitable alkyl radicals Z, Z₁ and Z₂ are especially unsubstituted alkylradicals having 1 to 4 carbon atoms.

Suitable aryl radicals Z₂ are in particular phenyl radicals, which maybe substituted by one or more halogen atoms, C₁-C₄-alkyl groups,C₁-C₄-alkoxy groups, cyano groups, carboxylic ester groups andcarboxamide groups.

Useful alkylene radicals Y are especially those having 2 to 4 carbonatoms such as

The anion A⁽⁻⁾ may be an anion of a low molecular weight organic acid,examples being formate and lactate.

Preferred pyrazoline brighteners are those of the formula

where

-   D is —CH₂CH₂—, —CH₂CH₂CH₂—, —CH₂CH₂OCH₂CH₂,-   R₁′ and R₂′ are each C₁-C₂-alkyl,-   T₁, T₂, T₃ are H, CH₃ or Cl and-   A is lactate or formate.

Preferably, T₁-T₃ do not represent C₁ or CH₃ at one and the same time.

The amount of these pyrazoline brighteners in the ready-prepared liquidformulation can be 1% to 60% and preferably 5% to 30% by weight.

The pyrazoline bases which underlie the brightener salts defined aboveare known and are described for example directly or indirectly (asquaternary salts) in the following patent literature: DE-A 1 155 418, 1237 124, 1 469 222, 1 904 424, 2 011 552, 2 050 725, 2 248 772, 2 534180 and 2 700 996 and U.S. Pat. No. 3,131,079 and also 3 135 742. Aswell as the brightener salt, the liquid formulations of the inventionadditionally contain organic acids and branched mono- or di-alcohols.Useful organic acids include low molecular weight organic acids of thekind which are customary for salt formation of pyrazoline bases, forexample formic acid, acetic acid or lactic acid or mixtures of suchacids. The amount of these acids based on the ready-prepared liquidformulation is generally in the range from 20% to 60% and preferablyfrom 30% to 50% by weight.

The fraction of branched mono- or di-alcohol in the ready-preparedliquid formulation can be 15% to 40% and preferably 20% to 30% byweight. Preferred mono- or di-alcohols are neopentylglycol and tertiarybutanol.

In addition, the liquid formulations of the invention can contain theauxiliaries customary for optical brighteners, such as for examplehydrotropic agents (urea for example), solution-stabilizing agents(ethylene glycol diacetate for example), preservatives, water-solublecationic shading dyes, each in amounts of up to 10% by weight.

The liquid formulations of the invention are preferably prepared byadding the individual components of the formulation in the followingorder and mixing them in a suitable manner: organic acid, branched mono-or di-alcohol, brightener salt, water. Instead of the brightener salt itis also possible to start from the underlying base and to increase theamount of organic acid by the amount needed for salt formation.

The liquid formulations of the invention have an improved stability instorage compared with the hitherto customary commercial form. Thisimproved storage stability shows itself in that the color coordinates ofthese formulations rise distinctly less on prolonged storage inparticular.

The liquid formulations of the invention are used in a conventionalmanner for incorporation into spinning dopes for the production ofpolyacrylonitrite fibers in the so-called wet-spinning process or forbrightening ready-prepared acrylic fibers in an exhaust process.

EXAMPLES

A liquid formulation was prepared by intensively mixing the followingcomponents at room temperature in this order:

40 g of lactic acid; 6 g of formic acid; 23.3 g of neopentylglycol (90%pure); 19.2 g of brightener (about 79% pure); 11.5 g of water. Thebrightener used has the formula

This liquid formulation was tested for storage stability (measurement ofthe color coordinates x and y) together with a commercially availableliquid formulation of the same brightener. The commercially availableliquid formulation contains 21 g of methoxypropanol and 13.8 g of waterinstead of 23.3 g of neopentylglycol and 11.5 g of water with thecomposition otherwise identical to that of the formulation of theinvention.

The following x and y values were measured as a measure of stability forboth formulations: Inventive Commercial formulation material x value yvalue x value y value At the start 0.353 0.390 0.354 0.392 After 4weeks' 0.362 0.404 0.368 0.401 storage RT/dark After 4 weeks' 0.3630.402 0.402 0.425 storage 50° C./dark After 10 weeks' 0.383 0.433 0.3900.433 storage RT/dark After 10 weeks' 0.386 0.428 0.449 0.466 storage50° C./darkThese values show that the color coordinates rise distinctly less forthe formulation of the invention compared with the commercial material.This indicates superior stability for the inventive formulation, whichcontains neopentylglycol.

1. An aqueous liquid formulation comprising an organic acid, a branchedmono- or di-alcohol and a pyrazoline brightener of the formula

where X is O, SO₂, SO₂NZ or a direct bond, Y is an alkylene chain, Z isH or alkyl, R₁ and R₂ are singly an alkyl, cycloalkyl or aralkyl radicalor together the remaining members of an N-heterocycle, Z₁ is H or alkyl,Z₂ is H, alkyl or aryl, and A is an anion of an organic acid.
 2. Theaqueous liquid formulation according to claim 1, wherein the pyrazolinebrightener is a compound of the formula

where D is —CH₂CH₂—, —CH₂CH₂CH₂—, —CH₂CH₂—OCH₂CH₂,

R₁′ and R₂′ stand are independently C₁-C₂-alkyl, and T₁, T₂, T₃ standare independently H, CH₃ or Cl.
 3. The aqueous liquid formulationaccording to claim 1, wherein the organic acid is lactic acid, formicacid, or acetic acid or mixtures thereof.
 4. The aqueous liquidformulation according to claim 1, wherein the branched mono- ordi-alcohol is neopentylglycol or tertiary butanol.
 5. The aqueous liquidformulation according to claim 1, further comprising 20% to 60% byweight of the organic acid.
 6. The aqueous liquid formulation accordingto claim 1, further comprising 15% to 40% by weight of the branchedmono- or di-alcohol.
 7. The aqueous liquid formulation according toclaim 1, further comprising 1% to 60% by weight of the pyrazolinebrightener.
 8. The aqueous liquid formulation according to claim 1,further comprising at least one customary auxiliary.
 9. (canceled) 10.The aqueous liquid formulation according to claim 1, wherein Y is analkylene chain interrupted by O, S, CONH.
 11. The aqueous liquidformulation according to claim 2, wherein D is


12. The aqueous formulation according to claim 2, wherein A is lactateor formate.
 13. A method for brightening an acrylic fiber comprising thestep of incorporating an aqueous formulation according to claim 1 in thewet-spinning process or exhaust process for the acrylic fiber.
 14. Anacrylic fiber made in accordance with the method of claim
 13. 15. Amethod for brightening an acrylic fiber comprising the step ofbrightening the acrylic fiber with an aqueous formulation as claimed inclaim
 1. 16. An acrylic fiber made in accordance with the method ofclaim 15.